PSD Neutron Discrimination for Dose Monitoring Applications in Particle Therapy

This work presents an analytical and experimental study aiming to validate two implementations of neutron rejection in medical imaging applications, with particular focus on dose monitoring in hadrontherapy. This topic is of particular interest for carbon ion beam therapy, where the neutron background fluctuations challenge the prompt gammas profile identification associated to the Bragg peak. The first solution facilitates pulse shape discrimination: leveraging an ASIC, a dense waveform sampling is avoided, allowing the embedding of PSD analysis in a simple microcontroller. Preliminary experimental results demonstrate the possibility to perform PSD with our integrated circuit solution. An analytical model was also developed, that describes the sources of noise connected to the PSD calculation; the analytical model is in good agreement with our experimental measurements. The second solution, based on a integrated circuit, leverages the typical temporal structures of beams delivered by cyclotrones. Rejection of interaction generating the scintillation light outside a short gate correlated with prompt gamma photons time of arrival might allow to reduce the neutron background.